1. Field of the Invention
This invention relates to a control apparatus for connecting a local area network (LAN) to an information processing device and a method of controlling the LAN.
2. Description of the Related Art
For example, a LAN communication system conforming to IEEE 802.3 is constructed as described hereinafter. Each information processing system connected to a LAN is allocated a unique 6-byte address. A calling information processing system transmits a frame to a desired information processing system by specifying the latter unique address. Each address in the LAN is normally stored beforehand in the data base of the information processing unit or a read only memory (ROM). In a network called TCP/IP, a protocol known as ARP (address resolution protocol) is used to obtain an address in the LAN.
To monitor frames flowing over the LAN for the purpose of taking in frames only with the self-address, a LAN control processor (hereinafter, referred to as an LCP) is provided between the LAN and each information processing unit. The LCP is also provided with the function of transmitting frames. In one recent method of decreasing a load on the information processing system, the LCP is caused to realize a low-level protocol in the network by using firmware. With this method, however, the LCP has to deal with an increased amount of processing. This results in a delay in processing by the LCP in a large-scale system, which limits the amount of processing by the information processing unit.
As noted above, in conventional LAN systems, an increase in the amount of processing at the LCP between the LAN and the information processing unit leads to a delay in processing. This imposes limitations on the amount of processing by the information processing unit.
A related literature of the present invention is U.S. Pat. No. 4,887,075.